Abstract

Greenhouse gas emissions from hydroelectric dams are oftenportrayed as nonexistent by the hydropower industry, and havebeen largely ignored in global calculations of emissions fromland-use change. Brazil’s Tucuruí Dam provides an example with important lessons for policy debates on Amazonian development and on how to assess the global warming impact ofdifferent energy options. Tucuruí is better from the pointof view of power density, and hence greenhouse gas emissions per unit of electricity, than both the average for existing dams in Amazonia and the planned dams that, if all built, wouldflood 3% of Brazil’s Amazon forest. Tucuruí’s emission of greenhouse gases in 1990 is equivalent to 7.0–10.1 × 106 tons of CO2-equivalent carbon, an amount substantially greater than the fossil fuel emission of Brazil’s biggest city, São Paulo. Emissions need to beproperly weighed in decisions on dam construction. Althoughmany proposed dams in Amazonia are expected to have positivebalances as compared to fossil fuels, substantial emissionsindicated by the present study reduce the benefits often attributed to the planned dams.